How Astrophysics Division Assets Are Helping Planetary Science

Astrophysics Division assets have been used in the past to support planetary science research activities and planetary missions. This has been occurring for a long time and I want to highlight this great relationship that our two disciplines have continued to develop over the years. The appearance of comet Siding Spring (CSS) has provided an opportunity for a collaborative effort, which is just the most recent example of this cooperation.

"It is apparent that a renaissance of planetary science using astrophysics assets is underway. As director of the Planetary Science Division, I deeply appreciate how these two communities of scientist have started to work together in understanding the origin and evolution of our solar system and all the diversity of objects within."

Since the formation of our solar system, comets have been bombarding our inner planets, providing water and organic materials necessary for life. From the furthest reaches of our solar system, known as the Oort cloud, comet Siding Spring has travelled for more than a million years, and for the first time since it was formed, visited the inner solar system and passed within 80,000 miles (130,000 km) from the surface of Mars. NASA's Mars missions gave us the first opportunity to image and study the nucleus of a comet from the Oort cloud region. CSS passed close enough to Mars to blanket it with its cometary material. It has been estimated that this type of close passage of a comet to the planet Mars coming from the Oort cloud occurs about once in eight million years!

NASA spacecraft and ground-based observatories joined the Mars missions in studying this once-in-a-lifetime event and observing how the Martian upper atmosphere would respond to the interaction with the comet, helping us learn more about how comets may have seeded our planet with water and the organic material we call the building blocks for life.

Using data from prior observations by the Hubble Space Telescope (HST), the Spitzer Space Telescope, the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), Swift and ground-based telescopes, experts modeled the dust ejected from the comet that could pose a risk to our orbiting Mars spacecraft. It was determined that the risk to the orbital assets was low; however, the spacecraft still adjusted their orbits as a precaution, placing them on the other side of Mars during the period of greatest risk.

The Space Telescope Science Institute created extensive observing plans for the comet's encounter with Mars. Twenty-two HST orbits were planned around the encounter. The HST investigation teams worked together on the scheduling in order to maximize the science. The HST observation planning was coordinated with Mars Reconnaissance Orbiter characterization of the comet's nucleus, Chandra X-ray Observatory observations of comet coma X-ray emission, and Kepler Space Telescope light curves.

The comet Siding Spring event was tremendously successful due to combined resources of Planetary and Astrophysics Divisions and people. I want to express my extreme appreciation to all who were involved in the planning and execution of the coordinated observations. The data we obtained was unique and will be analyzed for years to come.

This effort is only one example of the ongoing collaborative efforts between the Astrophysics and the Planetary Science Divisions at NASA. Another recent example is a new Hubble program devoted to long-term monitoring of the outer planets and recently awarded with Director's Discretionary time. The "Hubble 2020: Outer Planet Atmospheres Legacy (OPAL) Program" was proposed to provide a legacy archive of global planetary atmospheres maps. Starting in cycle 22, imaging for two global maps each for Jupiter, Uranus and Neptune will be acquired, adding Saturn starting in 2018. All data will be immediately public, and global maps will be generated and made available via the HST High Level Science Products archive. This is big news for planetary science research, especially in the area of outer planets. This will add to a total of 29 orbits per year for cycles 22-24 and 41 orbits per cycle thereafter where Saturn observing campaigns are being planned.

Solar system observations have also been selected for other astrophysics assets such as the K2 mission. The K2 mission provides an opportunity to continue Kepler's groundbreaking discoveries in the field of exoplanets and expand its role into new and exciting astrophysical observations. Kepler's loss of a second spacecraft reaction wheel in May 2013 effectively ended data collection in the original Kepler field after four years of continuous monitoring. However, all other Kepler assets remain intact and can be used for the K2 mission. Both missions are founded on the proven value of long-baseline, high-cadence, high-precision photometry and exploit a large field of view to simultaneously monitor many targets.

K2 will use an innovative way of operating the spacecraft to observe target fields along the ecliptic for the next two to three years. Early science commissioning observations have shown an estimated photometric precision near 150 ppm in a single 30-minute observation, and a six-hour photometric precision of 40 ppm (both at V = 12). The K2 mission offers long-term, simultaneous optical observation of thousands of objects at a precision far better than is achievable from ground-based telescopes. Ecliptic fields will be observed for approximately 80 days enabling a unique exoplanet survey, which fills the gaps in duration and sensitivity between the Kepler and Transiting Exoplanet Survey Satellite (TESS) missions, and offers prelaunch exoplanet target identification for James Webb Space Telescope (JWST) transit spectroscopy. Astrophysics observations with K2 will include studies of young open clusters, bright stars, galaxies, supernovae, and asteroseismology.

While Kepler observations are of limited value to solar system science, K2 will provide opportunities for such observations. Generally, slow moving sources and major planets between V=4 and 20 will be possible targets. K2 has a funded GO program, accepting proposals twice a year and the NASA PDS and ADAP programs may be used for K2 data as well. All K2 targets are chosen by the community via the GO program and no K2 data has any exclusive use period.

We are happy to announce for K2 the following solar system proposals have been accepted:

• Kelley: Rotation Period of the Mars Flyby Comet C/2013 A1 (Siding Spring)
• Lisse: NASA CIOC K2 Campaign Comet Siding Spring Custom Aperture Proposal
• Schwamb: Rotational Periods of Kuiper belt Objects and Centaurs with K2

With the goal of engaging the planetary community in taking part in further potential observations, the mission office will host a workshop at the upcoming Division of Planetary Science (DPS) meeting through a collaboration of NASA's Astrophysics and Planetary Science Divisions.

The Spitzer Space Telescope is another Astrophysics Division asset that includes in its legacy solar system observations. After the successful completion of the five-and-a-half year cryogenic mission, Spitzer began its warm mission operation on July 28, 2009. The observatory and the 3.6 and 4.5-micron channels on the IRAC instrument continue to operate superbly. The observing efficiency remains high (>80%). All available time on the observatory is devoted to General Observer (GO) science. The highlights of the Spitzer warm mission solar system programs include 600 hours of Near Earth Objects observations, 105 hours of comets observations, 377 of asteroids and Kuiper Belt Objects (KBOs) observations and 140 hours of mission support.

I truly believe that the use of the Spitzer telescope will enable our planetary science community to be successful in their future proposals for the upcoming James Webb Space Telescope. Therefore, I am strongly encouraging the planetary science community to continue to propose for observing time on the Spitzer Space Telescope. Proposers should identify how their observations will contribute to the body of scientific knowledge needed to help refine planetary missions objectives and aid in the understanding of the origin and evolution of the targeted body. These projects should be of general and lasting importance to the broad planetary community with the Spitzer observational data yielding a substantial and coherent database. These campaigns should enable major science observing projects that create a substantial and coherent database of archived observations that can also be used by subsequent planetary researchers, including General Observers (GOs). Objects that are possible future mission targets as outlined in the most recent planetary decadal survey are also encouraged.

The expected visibility of planetary systems during the remaining warm mission is as follows. Accessibility is limited to satellites of the system in most cases due to brightness:

Mars

18 Mar 2015; 9 Sep - 16 Dec 2016

Jupiter

7 Feb - 19 Mar 2015; 9 Jul - 18 Aug 2015; 18 Mar - 27 Apr 2016; 17 Aug - 27 Sep 2016

Saturn

19 May - 26 Jun 2015; 22 Oct - 1 Dec 2015; 7 Jun - 15 Jul 2015; 11 Nov - 21 Dec 2016

Uranus

2 Mar - 10 Apr 2015; 4 Oct - 12 Nov 2015; 13 Mar - 21 Apr 2016; 15 Oct - 24 Nov 2016

Neptune

21 Jan - 1 Mar 2015; 22 Aug - 30 Sep 2015; 1 Feb - 11 Mar 2016; 31 Aug - 9 Oct 2016

Pluto

4 Jan 2015; 27 Jun - 4 Aug 2015; 6 Dec 2015 - 14 Jan 2016; 6 Jul - 14 Aug 2016

The James Webb Space Telescope (JWST) will enable a wealth of new scientific investigations in the near- and mid-infrared, with sensitivity and spatial/spectral resolution greatly surpassing its predecessors. The Science Working Group (SWG) of JWST has a dedicated effort to establish the scientific capabilities of this facility for solar system science; a new white paper provides a general overview and preliminary case studies (http://www.stsci.edu/jwst/doc-archive/white-papers). This paper, focuses on solar system science facilitated by JWST, discussing the most current information available concerning JWST instrument properties and observing techniques relevant to planetary science. It also presents numerous example observing scenarios for a wide variety of solar system targets to illustrate the potential of JWST science to the solar system community. This paper updates and supersedes the solar system white paper published by the JWST Project in 2010 (Lunine et al., 2010). It is based both on that paper and on a workshop held at the annual meeting of the Division for Planetary Sciences in Reno, NV in 2012.
In order to fully realize the potential of JWST for solar system observations, the SWG has recently organized 10 focus groups including: Asteroids, Comets, Giant Planets, Mars, Near Earth Objects, Occultations, Rings, Satellites, Titan, and Trans-Neptunian Objects, to explore various science use cases in more detail. The findings from these groups will help guide the project as it develops and implements planning tools, observing templates, and data pipeline and archive so that they enable a broad range of solar system science investigations.

Furthermore, a workshop was held at the 2014 DPS consisted of: 1) Presentations of findings from the focus groups, and 2) Discussion with the broader community to identify gaps in the focus-group science use cases and in envisioned observatory capabilities. These outputs from the workshop were used to inform ongoing development and pre-launch operational studies. More information on solar system observations with JWST and other observatory capabilities can be found in https://jwst.stsci.edu/.

For additional information on each instrument:

• MIRI: http://www.stsci.edu/jwst/instruments/miri/docarchive/miri-pocket-guide.pdf
• NIRCam: http://www.stsci.edu/jwst/instruments/nircam/docarchive/NIRCam-pocket-guide.pdf
• NIRSpec: http://www.stsci.edu/jwst/instruments/nirspec/docarchive/NIRSpec-pocket-guide.pdf
• NIRISS: http://www.stsci.edu/jwst/instruments/niriss/docarchive/NIRISS-pocket-guide.pdf

These missions are preparing to provide tutorials and workshops on the use of the instruments and proposal software. The Planetary Science Division has created a team of discipline scientists to help shepherd this effort. Look for them at the Division for Planetary Sciences (DPS), the Lunar and Planetary Science Conference (LPSC) and the American Geophysical Union (AGU).

It is apparent that a renaissance of planetary science using astrophysics assets is underway. As director of the Planetary Science Division, I deeply appreciate how these two communities of scientist have started to work together in understanding the origin and evolution of our solar system and all the diversity of objects within. When we look at the sky at night, we now know that the stars we see have solar systems similar to our own. This is the new paradigm that has drawn us more closely together.